title: Vaginolysin drives epithelial ultrastructural responses to Gardnerella vaginalis.
abstract: Gardnerella vaginalis, the bacterial species most frequently isolated from women with bacterial vaginosis (BV), produces a cholesterol-dependent cytolysin (CDC), vaginolysin (VLY). At sublytic concentrations, CDCs may initiate complex signaling cascades crucial to target cell survival. Using live-cell imaging, we observed the rapid formation of large membrane blebs in human vaginal and cervical epithelial cells (VK2 and HeLa cells) exposed to recombinant VLY toxin and to cell-free supernatants from growing liquid cultures of G. vaginalis. Binding of VLY to its human-specific receptor (hCD59) is required for bleb formation, as antibody inhibition of either toxin or hCD59 abrogates this response, and transfection of nonhuman cells (CHO-K1) with hCD59 renders them susceptible to toxin-induced membrane blebbing. Disruption of the pore formation process (by exposure to pore-deficient toxoids or pretreatment of cells with methyl-β-cyclodextrin) or osmotic protection of target cells inhibits VLY-induced membrane blebbing. These results indicate that the formation of functional pores drives the observed ultrastructural rearrangements. Rapid bleb formation may represent a conserved response of epithelial cells to sublytic quantities of pore-forming toxins, and VLY-induced epithelial cell membrane blebbing in the vaginal mucosa may play a role in the pathogenesis of BV.
authors.affiliation: Department of Pediatrics, Columbia University, New York, New York, USA.
authors.forename: Tara M
authors.initials: TM
authors.lastname: Randis
authors.forename: Joanne
authors.initials: J
authors.lastname: Zaklama
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: LaRocca
authors.forename: Ferdinand C O
authors.initials: FC
authors.lastname: Los
authors.forename: Emma L
authors.initials: EL
authors.lastname: Lewis
authors.forename: Purnahamsi
authors.initials: P
authors.lastname: Desai
authors.forename: Ryan
authors.initials: R
authors.lastname: Rampersaud
authors.forename: Fábio E
authors.initials: FE
authors.lastname: Amaral
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Ratner
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D001427:Bacterial Toxins / Q000378:metabolism*; D018957:CD59 Antigens / Q000378:metabolism; D016466:CHO Cells; D022081:Cell Surface Extensions / Q000382:microbiology*; D002584:Cervix Uteri / Q000166:cytology / Q000276:immunology / Q000382:microbiology; D003412:Cricetulus; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D005260:Female; D006194:Gardnerella vaginalis / Q000254:growth & development / Q000276:immunology / Q000378:metabolism*; D016908:Gram-Positive Bacterial Infections; D006367:HeLa Cells; D006801:Humans; D015398:Signal Transduction; D014621:Vagina / Q000166:cytology / Q000276:immunology / Q000382:microbiology; D016585:Vaginosis, Bacterial / Q000276:immunology* / Q000382:microbiology; D047392:beta-Cyclodextrins
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D018957:CD59 Antigens; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C542392:vaginolysin, Gardnerella vaginalis